Prince Charles called Queen Elizabeth to ask about her health before embarking on a royal tour to Jordan.
The 95-year-old monarch has been urged to rest by her doctors after suffering a back sprain, and Charles called his mother over the weekend to see how she's feeling.
A royal source told the Daily Mirror newspaper: "The Prince of Wales made sure to check in with the Queen ahead of his departure and was completely reassured of her current condition by Her Majesty herself.
"The Queen is resting at Windsor Castle and will continue to do so until she is back to full health.
"Straining your back can be incredibly debilitating and rest is best right now."
Prince Charles laid a wreath on behalf of the Queen at the Cenotaph in London on Sunday (11.14.21).
The 73-year-old royal was joined at the war memorial by various members of the royal family, including the Duchess of Cornwall, the Duke and Duchess of Cambridge, and the Earl and Countess of Wessex - but the Queen was absent from the Remembrance Sunday service after spraining her back.
The monarch had intended to attend the event after recently been advised to rest by her doctors.
However, news of her absence was confirmed on the morning of the service.
Buckingham Palace said in a statement: "The Queen, having sprained her back, has decided this morning with great regret that she will not be able to attend today's Remembrance Sunday service at the Cenotaph.
"Her Majesty is disappointed that she will miss the service."
The monarch has only missed six other Cenotaph ceremonies during her reign, but the palace revealed that the Queen will be continuing with light duties at Windsor Castle.